Mar 25, 2002 (CIDRAP News)  It is 13 days since the emergence of a hypothetical smallpox epidemic caused by the release of virus in three US shopping malls. Some 16,000 cases have been reported, 1,000 people have died, and the nation is running out of vaccine. Hospitals are overflowing, and federal and state officials are at odds over how to contain the epidemic.

That was the situation near the end of "Dark Winter," a simulation exercise in which government and health officials were faced with an imaginary bioterrorist attack involving smallpox virus. The exercise was staged in June 2001, a few months before real bioterrorism materialized in the form of the anthrax attacks in October. Experts from the Center for Civilian Biodefense Strategies at Johns Hopkins University describe and analyze the exercise in the April 1 issue of Clinical Infectious Diseases.

The exercise found the nation ill-prepared in several ways to deal with a smallpox epidemic, according to the analysts (two of whom helped design the exercise). Besides spotlighting the problems mentioned aboveshortages of vaccine and hospital capacity and conflicts between federal and state authoritiesthe exercise showed that leaders just didn't know much about the likely consequences of a bioterrorist attack.

"Dark Winter" was a 2-day tabletop exercise in which 12 current and former high-level government and military officials portrayed members of the National Security Council. The players were presented with the smallpox scenario and asked to make policy decisions, which were then incorporated into the further development of the scenario.

The scenario assumed that 3,000 people were infected with smallpox by simultaneous release of the virus in shopping malls in Oklahoma City, Philadelphia, and Atlanta. On the basis of European smallpox outbreaks between 1958 and 1973, the designers of the exercise assumed that each infected person would infect 10 more people. These two assumptions were based on existing information about smallpox but "were not intended to be definitive mathematical predictors or models," the authors state. Further, the designers assumed that only about 20% of the US population still had some immunity to smallpox from childhood vaccinations. The players were told to assume that 12 million doses of vaccinemost of the CDC's stockpile (at the time) of 15.4 million doseswere available and that vaccination within 4 to 5 days after exposure may prevent or ameliorate the disease. (Acambis Inc. now is under contract to produce 209 million doses of smallpox vaccine for the US stockpile, and federal officials also hope to
increase the existing number of doses by diluting the vaccine.)

The exercise posited that terrorists released smallpox virus on or about Dec 1 and that, given the diseases's 9- to 17-day incubation period, the NSC was informed of the outbreak on Dec 9. The outbreak began with the confirmation of 20 cases in Oklahoma and news of suspected cases in Georgia and Pennsylvania. In response, the NSC members decided to fully inform the public of the situation, to focus initial vaccination efforts on patient contacts and healthcare and public safety personnel in the affected states (ring vaccination), and to set aside a supply of vaccine for the Department of Defense, estimating that the department would need about 1 million doses.

By Dec 15, 6 days after the outbreak was reported to the NSC, 2,000 smallpox cases and 300 deaths were reported in 15 states, and isolated cases were reported in Canada, Mexico, and the United Kingdom. Only 1.25 million doses of vaccine remained, and vaccine distribution efforts in some states were chaotic and marred by violence. The NSC members decided to launch a crash program to produce vaccine and to accept vaccine offered by Russia. At a press conference, the president appealed to the people to work together and to follow the guidance of public health officials.

Matters were worse by Dec 22, or day 13 of the scenario. With 16,000 US cases, the vaccine supply was gone, and no new supply was expected for at least 4 weeks. States were restricting nonessential travel, food shortages were growing in some areas, and the economy was suffering. The public demanded isolation of smallpox patients and their contacts, but identifying contacts had become "logistically impossible." Health experts advised the NSC that they expected to succeed in containing the epidemic. However, the experts said that in the worst caseie, if no more vaccine became available and systematic, broad containment measures could not be implementedthe epidemic could lead to 3 million cases and 1 million deaths. The scenario finally ended with the announcement that anonymous letters to three major newspapers had demanded the removal of all US forces from Saudi Arabia and the Persian Gulf.

The authors present seven lessons from the scenario, all based on comments and decisions by the participants during the exercise and on their later congressional testimony and public statements:

"Leaders are unfamiliar with the character of bioterrorist attacks, available policy options, and their consequences." Oklahoma Gov. Frank Keating, a participant, said, "This was very revealing to methat there is something out there that can cause havoc in my state that I know nothing about."

"After a bioterrorist attack, leaders' decisions would depend on data and expertise from the medical and public health sectors." The players often wanted information that was not immediately available, such as the sites of the attacks and a forecast of the likely size of the epidemic on the basis of the first cases.

The lack of enough vaccine or drugs to prevent the spread of disease severely limited management options." The shortage of vaccine "led to great public anxiety and flight by people desperate to get vaccinated."

The healthcare system lacks the capacity to deal with mass casualties. The challenge of distinguishing the sick from the worried well, rationing scarce resources, and dealing with staff shortages and staff members worried about their own health posed a huge burden on the system.

"To end a disease outbreak after a bioterrorist attack, decision makers will require expert ongoing advice from senior public health and medical leaders." Some NSC members favored geographic quarantines around affected areas, but didn't clearly understand the implications of those measures at first.

"Federal and state priorities may be unclear, differ, or conflict; authorities may be uncertain; and constitutional issues may arise." Tensions quickly developed between state and federal authorities over access to vaccine and other disease-containment measures, such as isolation. "My fellow governors and I are not going to permit you to make our states leper colonies," said Keating.

Because the actions of individuals will be critical in fighting an epidemic, leaders must gain the trust and sustained cooperation of the people. "There is no federal force out there that can require 300 million people to take steps they don't want to take," said Sam Nunn, participant and former senator.